U.S. Pat. No. 3,815,129, issued to Sweany and hereby incorporated by reference, discloses an exemplary feedback type piezoelectric transducer. Piezoelectric transducers, such as those disclosed in the '129 patent, are typically disposed within a housing constructed to maximize transmission of sound into the ambient medium. As shown in FIGS. 1, 2 and 5 of the '129 patent, such transducers have a piezoelectric element mechanically coupled to a substrate, such as a brass disc. The piezoelectric element includes a piezoelectric crystal. The element also has electrode means carried on the crystal or the substrate. The electrode means are electrically connected to electrical terminals. In the '129 patent, these terminals are labeled T.sub.1, T.sub.2 and T.sub.3. T.sub.1 and T.sub.2 are driving terminals for receiving oscillating driving potentials, and T.sub.3 is a feedback terminal that allows the transducer itself to cooperate with an electrical circuit as a reactive impedance. T.sub.2 is connected to the electrode means located on the substrate opposite T.sub.1 and T.sub.3, a brass plate that forms a disc and acts as a diaphragm.
In typical use, all of the above parts are completely enclosed in a housing. The transducer is sealed with a silicon type of material between the brass side of the transducer and the nodal ring that defines the inner surface of the housing. The respective terminals extend outside the housing on one end. The end from which the terminals extend is attached onto a PC board, with the terminals attached to appropriate contacts via a solder connection. The PC board contains the components of the electrical circuit that, like in FIGS. 3 and 4 of the '129 disclosure, enable the noise making device to function.
Heretofore, it was not known to make any electrical connection extending outwardly from the PC board through the transducer housing and to the end of the housing opposite the PC board. Once the housing holding the transducer elements was attached to the PC board, electrical access to any electrical contacts on the PC board was extremely difficult to achieve. The transducer housing took up most of the surface of the PC board and blocked the way. This caused many disadvantages. Among the disadvantages, it was difficult to expand the circuit to include other electrical components that are not necessary to the sound generating function. This made it nearly impossible to add such electrical components to enhance the functionality of the noise making unit, such as light emitting devices or other actuator components. It was also unfeasible to dispose existing or new electrical components on the surface of the transducer housing. While placing such electrical components on the surface of the transducer housing was possible in principle, to do so would formerly require snaking a conductor such as a flying lead wire around the surface of the housing. This approach risks breakages and open circuits. Such an approach also would be expensive to manufacture. Furthermore, a problem to be overcome was how to extend an electrical contact to the PC board through the tight spaces inside the transducer housing without attenuating or degenerating the sound quality emitted by the brass disc diaphragm.